The story begins with the invocation to the Muse. What is the purpose of this section in The Odyssey?
This part of the epic poem functions as a sort of prayer: Homer prays to the muse of epic poetry, a daughter of Zeus named Calliope, to "Sing to him" of Odysseus, to "Launch out on his story," starting wherever she would like to begin. Homer prays for the muse's assistance in the telling of this story, and this beginning certainly helps to illustrate what an integral part of life the immortals were for the ancient Greeks. One might not sing a song, recite a poem, or even eat a meal without making some offering, verbal or otherwise, to them. Further, this section serves as a kind of prelude to the events which follow: Odysseus travels far and wide, learning, suffering, and desiring to return home. However, "he could not save [his crew] from disaster," and they are destroyed by their own "recklessness." They "devoured the cattle of the Sun" and suffer the consequences.
If you are in 9th grade, I am assuming you are reading a retelling of The Odyssey in your literature book.
In that first section, Homer calls on the Muse of epic poetry to help him tell the story of Odysseus. A muse is like an inspiring spirit that can get into a person and help motivate them to do what it is they desire to do. For Homer, it's tell a story in the form of poetry.
Here, Homer reveals to us the purpose for telling his story, so that we can all know of the great character Odysseus' traits and how he used them. He tried to get his men back to their homeland, but the men did not always listen to their leader and this was their downfall. Already, in the invocation, we are learning about what the storyline will look like, what will ultimately happen to the men, and we learn a lesson - obeying authority might be a handy tool in life.